Method of Manufacturing Plastic Clips

ABSTRACT

A method of manufacturing clips is described, The method comprises the steps of extruding a incited thermoplastic resin into thin extrudate and forming the extrudate into a plurality of clips. The forming step comprises one of (a) a step of vacuum thermoforming the extrudate into a plurality of clips by pulling the extrudate over a female mold and pulling a vacuum between the mold and the extrudate; or (b) the steps of providing a forming tool perpendicular to the extrudate, the extruding tool having a shape corresponding to the inside of a single clip; forming the single clip by contacting the extrudate with the forming tool and retracting the forming tool; advancing the extrudate; forming a second single clip by contacting the extrudate with the forming tool and retracting the forming tool; and cooling the formed clips.

PRIORITY

This application is a division of U.S. patent application Ser. No.12/204,182, filed Sep. 4, 2008, which claimed the benefit of U.S.Provisional Patent Application No. 60/974,983, filed Sep. 25, 2007, thedisclosure of each of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates to the field of packaging material in tubularfilm, bags, or netting. The invention relates more particularly topackaging food materials, such as pasty food materials, in tubular film,and to packaging food materials, such as poultry, in bags and/ornetting.

Food material such as sausage, cookie dough, and polenta is packaged byextruding the pasty material through a product horn and into a tubularfilm. One preparation system uses film already formed in a tube, such asis described in U.S. Pat. No. 7,063,610, Apparatus And Method To NetFood Products In Shirred Tubular Casing, the disclosure of which isincorporated herein by reference. Another preparation system uses flatsheets of film, which is turned over plows and guides and formed into atube as the pasty food product is extruded, such as is described in U.S.Pat. No. 4,958,477, Apparatus for the Production of Meat Products, thedisclosure of which is incorporated herein by reference. In eithersystem, the chubs or sausages formed in the process are closed at eachend by a clip.

Food material such as poultry, whether whole birds or parts, is packagedby placement into bags, such as is described in U.S. Pat. No. 6,895,726,Poly-stretch Bagger System, the disclosure of which is incorporatedherein by reference. The bag in this situation is closed with a clip.

Other types of food materials, such as hams, are enclosed in netting,either with or without a film, such as is described in U.S. Pat. No.6,883,297. Apparatus for Enclosing Material in a Wet, the disclosure ofwhich is incorporated herein by reference. The net, and film, if it isused, are closed with a clip in this situation.

Conventional clips for each of these processes are made of metal,typically aluminum. The clips are typically formed from wire by a clipmanufacturer and are supplied to the food manufacturer in sticks or inreels, in other processes, wire from a reel is wrapped around the neckof the tubular film and severed, to seal the tubular film.

Food manufacturers desire to keep metal out of their products.Accordingly, one manufacturing practice for making food, particularlypasty food products such as sausage, cookie dough, or polenta, is to runthe pasty food product through a metal detector. Since the clips used toenclose the food products are made of metal, the metal detecting stepmust come before the stuffing step. Accordingly, a conventionalfood-making operation will have first a food mixer in which the sausagemeat, cookie dough, or polenta is prepared. The pasty food mixture isthen pumped via a plastic or glass pipe to a metal detector, which scansfor the presence of metal. The pasty food mixture, if free of metal,then continues to a clipper/stuffer, where the mixture is formed intochubs or sausages by, for example, one of the processes described in thepatents listed previously.

Some food manufacturers prefer to scan the completed food products formetal, rather than scanning the raw pasty mixture. This practice doesnot permit the use of metal clips. Plastic clips must be used in thissituation. Plastic clips are typically formed into reels or sticks byinjection molding. The reels or sticks are then used in the machinesdescribed in the patents listed previously.

Similarly, in some situations food manufacturers wish to irradiate foodproducts, to destroy microorganisms, bacteria, viruses, or insects. Inthese situations, the use of metal clips is contraindicated. In yetother situations, it is desirable that the food products not be sealedby metal clips.

A need exists for enclosing food products, including but not limited tosausages or chubs, with plastic clips in an easy and inexpensive manner.The present invention meets this need.

BRIEF SUMMARY OF THE INVENTION

The present invention comprises a method of manufacturing clips. Themethod comprises the steps of extruding a melted thermoplastic resininto thin extrudate and forming the extrudate into a plurality of clips.The forming step comprises one of (a) a step of vacuum thermoforming theextrudate into a plurality of clips by pulling the extrudate over afemale mold and pulling a vacuum between the mold and the extrudate, or(b) the steps of providing a forming tool perpendicular to theextrudate, the extruding tool having a shape corresponding to the insideof a single clip; forming the single clip by contacting the extrudatewith the forming tool and retracting the forming tool; advancing theextrudate; forming a second single clip by contacting the extrudate withthe forming tool and retracting the forming tool; and cooling the formedclips.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The organization and manner of the structure and operation of theinvention, together with further objects and advantages thereof, maybest be understood by reference to the following description, taken inconnection with the accompanying non-scale drawings, wherein likereference numerals identify like elements in which:

FIG. 1 is an elevation view of a series of clips as used in thepreferred embodiment of the invention.

FIG. 2 is a diagrammatic view of the sausage-making system of thepresent invention.

FIG. 3 is a perspective view of the die system of the preferredembodiment of the present invention, with the die and punch in a first,adjacent position.

FIG. 4A is a plan view of the punch of the die system of FIG. 3.

FIG. 4B is a plan view of the die of the die system of FIG. 3.

FIG. 5 is an elevation view of the die system and the knife system of anembodiment of the present invention, with the die and punch in a second,remote position.

FIG. 6 is a cross-sectional view of a clip inside the groove of the diesystem of FIG. 3.

FIG. 7 is a perspective view of the die system of FIG. 3 enclosing aneck of gathered casing and netting captured by the die system of thepreferred embodiment of the invention.

FIG. 8A is a side elevation view of a clip as closed by the apparatus ofFIG, 2.

FIG. 8B is a top plan view of the clip of FIG. 8A.

FIG. 9A is an embodiment of an apparatus for making extruded clips foruse in the apparatus of FIG. 2.

FIG. 9B is a closer view of the forming tool of the apparatus of FIG.9A.

FIG. 10A is a side view of a stick of molded clips for use in theapparatus of FIG. 2.

FIG. 10B is a side view of an individual clip of the stick of FIG. 10A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

While the invention may be susceptible to embodiment in different forms,there is shown in the drawings, and herein will be described in detail,specific embodiments with the understanding that the present disclosureis to be considered an exemplification of the principles of theinvention, and is not intended to limit the invention to that asillustrated and described herein. The embodiments described herein applyto forming a sausage or chub from a pasty filling in a clipper/staffer,but the invention can also be used to enclose other material, such ascookie dough or polenta, in tubular casing, to enclose sausages innetting, to enclose materials such as whole-muscle meats or hardsausages in film and/or netting, to enclose other material, includingnon-food material, in film, netting, or bags, and in any other situationin which a plastic clip is preferred.

The preferred embodiment of the present invention uses packageenclosures to close tubular film or netting. Package enclosures asdescribed herein comprise a series 20 of connected plastic clips 22. Aseries 20 of clips 22 is supplied to a customer on a stick, a spool, ora reel. Clips 22 can be formed in a particular color and can havedesignating information imprinted thereon, Clips 22 are preferablyextruded from a thermoplastic such as polyethylene or polypropylene. Inother embodiments, another material not opaque to x-rays or sterilizingradiation is used. In yet other embodiments, clips 22 are injectionmolded.

The preferred embodiment of clips 22 is shown in side elevation view inFIG. 1. Each clips 22 has an arched shape with a curved or semicircularfirst section 24, two bending sections 26 extending from first section24, and a connecting section 28 extending from each bending section 26,Each connecting section 28 connects to a connecting section 28 of anadjacent clip 22 (except the first and last clip 22 of a series 20).

Series 20 of clips 22 are used in the illustrated embodiment in asausage-making system 30, as shown diagrammatically in FIG. 2. System 30comprises a mixing chamber 32, a stuffer 34, a die system 36, and acontroller 38.

Mixing chamber 32 is preferably a conventional mixer used to make apasty filling for sausages. Mixing chamber 32 delivers the pasty fillingto sniffer 34, an apparatus capable of encasing material, such as pastyproducts, into fibrous, collagen, or plastic casing. Stuffer 34 ispreferably a Poly-clip System Corp ICA 8700 automatic double clipper. Inother embodiments, sniffer 34 also comprises a netter. In yet otherembodiments, mixing chamber 32 is replaced by a delivery system forother material as described above, to be encased in film or netting instuffer 34.

In the illustrated embodiment, stuffer 34 encases the pasty filling intocasing in a conventional manner. The casing can be a preformed tubularfilm or can be formed into tubes from flat sheets of roll stock film.Die system 36 encloses the pasty filling in the casing by applying aclip 22 at each end of a sausage or between each of a series of chubs toform the finished product.

Controller 38 is coupled to and controls the operations of mixingchamber 32, stuffer 34, and die system 36. Controller 38 is preferably aprogrammed logic controller, analog controller, computer, ormicroprocessor. In one embodiment, controller 38 is a Siemens centralprocessing unit, with a “power 5 6EP1333-1SL11” power supply, a “SimaticS7-300 314-1AEO4-0AB0” PLC, a 32-output “SM322 321-1BL00-0AA0” card, a32-input “SM 321 321-ABL00-0AA0” card, and a 16-input “SM 321321-1BH0S-0AA0” card.

In another embodiment, controller 38 is a PLC controller having anindexer, preferably a Commander SK AC drive with LogicStick, such as onesold by Control Techniques division of Emerson Electric Co. TheLogicStick provides PLC functionality and is preferably programmed usinga PC/laptop computer with SyPTLite software and a CT Comms Cableconnecting lead.

In yet another embodiment, controller 38 is a command controller. In yetanother embodiment, system 30 is operated manually.

Die system 36 has a punch 50 and die 52, as shown in, for example, FIGS.3, 4A, and 4B. Punch 50 moves in a reciprocating manner from a firstposition, adjacent to die 52, as shown in, for example, FIG. 3, to asecond position, remote from die 52, as shown in FIG. 5. Preferably, inthe first position, punch 50 is flush or nearly flush with die 52.

Punch 50 preferably is moved between positions by an air-actuatedcylinder 54. Cylinder 54 preferably runs off plant air and is controlledby controller 38. In other embodiments, punch 50 is situated at the endof a lever arm which swings, manually or by actuation of cylinder 54, tomove punch 50 between positions. In yet another embodiment, punch 50 ismoved between positions manually.

Similarly, die 52 moves in a reciprocating manner from a first position,adjacent to punch 50, as shown in, for example, FIG. 3, to a secondposition, remote from punch 50, as shown in FIG. 5. Preferably, in thefirst position, die 52 is flush or nearly flush with punch 50. Die 52preferably is moved between positions by an air-actuated cylinder 56.Cylinder 56 also preferably runs off plant air and is controlled bycontroller 38. In other embodiments, die 52 is situated at the end of alever arm which swings, manually or by actuation of cylinder 56, to movedie 52 between positions. In yet another embodiment, die 52 is movedbetween positions manually.

In the preferred embodiment, both punch 50 and die 52 move relative tostuffier 34. In another embodiment, die 52 is stationary with respect tostuffer 34 and only punch 50 moves between a first position and a secondposition.

Punch 50 is a solid block, as shown in FIG. 3. Punch 50 has peripheralface 60 on a side opposite the connection of cylinder 54 to top die 50,as shown in FIG. 4A. A half-cylindrical bore 62 forms an arcuate wall64, separating a first side 66 of peripheral face 60 from a second side68 of peripheral face 60. A pair of parallel grooves 70, 72 is formed inarcuate wall 64, extending from first side 66 to second side 68.

Die 52 has a peripheral face 80 on a side facing peripheral face 60 ofpunch 50, as shown in FIG. 4B. A half-cylindrical bore 82 forms anarcuate wall 84 in peripheral face 80, separating a first side 86 ofperipheral face 80 from a second side 88 of peripheral face 80. A singlegroove 90 is formed in die 52. Groove 90 extends from first side 86,through arcuate wall 88, through second side 88, and through out outeredge 92 of die 52, thereby forming slot 94 in die 52.

When die 52 is in its remote position, as shown in FIG. 5, slot 94 isopen on outer edge 92 and peripheral face 80. Series 20 of clips 22 arefed to die 52. A single clip 22 moves through slot 94 and sets in groove90, as shown in sideways cross-section in FIG. 6. The remaining clips 22of series 20 remain outside die 52.

Voider gates or irises on stiffer 34 form a neck 100 of gathered casingover bore 82. Controller 38 causes die 52 to ascend to its secondposition, thereby capturing neck 100 within clip 22. Controller 38 thencauses punch 50 to descend to its second position, in which peripheralface 60 is flush or nearly flush to peripheral face 80, therebyenclosing neck 100 within the passageway 102 formed by bore 62 and bore82. FIG. 7 shows a neck of gathered netting and casing enclosed withinpassageway 102, with clip 22 not shown for clarity.

As punch 50 descends, groove 70 captures one connecting section 28 ofclip 22 and groove 72 captures the other connecting section 28 of clip22, forcing both connecting sections 28 to bend inward toward eachother, thereby causing bending sections 26 also to bend inward, therebyforming open clip 22 into the dosed position, shown in side elevationview in FIG. 8A and in top plan view in FIG. 8B.

In the preferred embodiment, the punching action of punch 50 will breakconnecting section 28 from the connecting section 28 of the next clip 22in series 20. In another embodiment, a knife system 110 is mounted todie system 36, as shown in FIG. 5. Knife system 110 has a knife 112having a knife edge 114. Knife 112 moves in a reciprocating manner froma first position, remote from slot 94, to a second position adjacentslot 94. Knife 120 preferably is actuated to move between positions byan air-actuated cylinder 116, controlled by controller 38. In otherembodiments, knife 112 is situated at the end of a lever arm whichswings, manually or by actuation of cylinder 116, to move knife 112between positions. When knife 112 moves from the first position to thesecond position, knife edge 114 eclipses the opening to slot 94 andsevers connecting section 28 of the dip 22 held within groove 90, fromconnecting section 28 of the next clip 22 in the series 20.

In a first embodiment of sausage-making system 30, there is a single diesystem 36. Repeated periodical application of clips 22 to gathered necks100 of casing thereby forms a line of chubs. In another embodiment,there is a pair of die systems 36 mounted adjacent stuffer 34. When thevoider gates or irises of stuffer 34 form a neck 100 of gathered casing,each die system 36 applies a separate clip 22 to neck 100 and a separateknife from stuffer 34 severs neck 100 between the two clips 22, one ofwhich forms the back end of a sausage and one of which forms the frontend of the next sausage to be made.

Clips 22 are preferably formed of a thermoplastic polymer, mostpreferably polypropylene, by an extrusion process. In anotherembodiment, clips 22 are molded. Clips 22 are preferably circular incross section, as shown in FIG. 6. In other embodiments, clips 22 haveother cross-sectional shapes.

An apparatus for forming clips 22 by an extrusion process is shown inFIGS. 9A and 9B. A thermoplastic resin is melted and extruded fromextruder 120, a conventional extruder having, for example, a feedhopper, a screw drive or other drive system, a heater, and a die 122located on the head 124 of extruder 120. The thermoplastic resin ismelted and formed into a thin extrudate 126. Extrudate 126 preferablyhas a circular cross-section as it exits die 122. In other embodiments,extrudate 126 has a rectangular cross-section or a polygonalcross-section, such as hexagonal. Other cross-sectional shapes arepossible, depending on the final application.

Extrudate 126 enters a vacuum calibration station 128. Extrudate 126 isvacuum thermoformed in station 128 into individual clips 22, forming aseries 20 of clips 22, such as the series 20 shown in FIG. 1. In oneembodiment, extrudate 126 is pulled over a female mold and a vacuum ispulled between extrudate 126 and the mold. In another embodiment,forming tool 130 is used to form clips 22, as shown in FIG. 9B. Formingtool 130, configured to actuate perpendicular to extrudate 126, has theshape of the inside of clip 22. Forming tool 130 is configured to formextrudate 126 into whatever shape is desired for the final applicationof clip 22.

Forming tool 130 descends to form extrudate 126 in the shape of clip 22,then retracts as extrudate 126 advances, then descends again to form thenext clip 22 in the series 20. In either embodiment, series 20 continuesthrough station 128, where it is cooled, and continues out of station 12where it is gathered onto a reel 132.

An embodiment of molded clips is shown in FIGS. 10A. In this embodiment,a stick 140, as shown in FIG. 10A, of individual clips 142, as shown inFIG. 10B, is molded preferably from a thermoplastic polymer, mostpreferably polypropylene. Each clip 142 has a top section 144 with aninternal face 146 and an external face 148. As illustrated, top section144 is generally rounded, but it can be straight and can have sharpcorners if desired. Two legs 150, 152 extend from opposite ends of topsection 144. Accordingly, legs 150, 152 and top section 144 define aspace 154 within clip 142.

Each leg 150, 152 terminates, at an end opposite top section 144, in afoot section 156. Each foot section 156 has a protrusion 158 extendinginto space 154. Legs 150, 152 preferably are narrower in frontcross-section, at an end having protrusion 158, than at an end meetingtop section 144. Preferably, outer edge 160 of leg 150 is parallel toouter edge 162 of leg 152, so that the narrowing of each leg 150, 152occurs from sloping of inner edge 164 of leg 150 and inner edge 166 ofleg 152, relative to outer edges 160, 162, respectively.

Each clip 142 is preferably approximately 200 millimeters deep. Eachouter edge 160, 162 has a connecting portion 168 projecting outwardly.Each connecting portion 168 is joined to a Connecting portion 168 of anadjacent clip 142 (except on the first and last clip 142 in a stick 140)to form stick 140. In use, each connecting portion 168 will easily snapfrom adjacent connecting portion 168, allowing an individual clip 142 tobe removed from stick 140.

In another embodiment, connecting portion 168 projects from a differentportion of clip 142, such as from top section 144.

Clip 142 can have a projecting shoulder 170, to enhance alignment, asshown in FIG. 10B. Clip 142 can also have a pin 172 projecting intospace 154, as shown in FIG. 10B, to enhance the grip on clip 142 on theneck 100 of packaging.

While preferred embodiments of the present invention are shown anddescribed, it is envisioned that those skilled in the art may devisevarious modifications of the present invention without departing fromthe spirit and scope of the appended claims.

I claim:
 1. A method of manufacturing clips, comprising the steps of:extruding a melted thermoplastic resin into thin extrudate; andthermoforming the extrudate into a plurality of clips.
 2. The method ofclaim 1, wherein the forming step comprises one of a step of vacuumthermoforming the extrudate into a plurality of clips by pulling theextrudate over a female mold and pulling a vacuum between the mold andthe extrudate; or the steps of providing a forming tool perpendicular tothe extrudate, the extruding tool having a shape corresponding to theinside of a single clip; forming the single clip by contacting theextrudate with the forming tool and retracting the forming tool;advancing the extrudate; forming a second single clip by contacting theextrudate with the forming tool and retracting the forming tool; andcooling the formed clips.
 3. The method of claim 2, further comprisinggathering the plurality of clips onto a reel.
 4. The method of claim 2,wherein the clips each comprise a top section having an internal face,an external face, and opposite ends, the clips each further comprise twolegs extending from the opposite ends, each leg having an outer edge andan inner edge, and each leg further comprises a connecting portionprojecting outwardly from the outer edge of each leg, at least oneconnecting portion of each clip being joined to a connecting portion ofan adjacent clip.
 5. The method of claim 2, wherein each clip furthercomprises a shoulder projecting outwardly from the external face.
 6. Themethod of claim 2, wherein a space is defined by the internal face andthe inner edges of each leg of each clip and each clip further comprisesa pin projecting into the space.
 7. The method of claim 6, wherein aspace is defined by the internal face and the inner edges of each leg ofeach clip and each clip further comprises a pin projecting into thespace.
 8. A method of manufacturing clips, comprising the steps of:extruding a melted thermoplastic resin into thin extrudate; vacuumthermoforming the extrudate into a plurality of clips by pulling theextrudate over a female mold and pulling a vacuum between the mold andthe extrudate.
 9. The method of claim 8, further comprising gatheringthe plurality of clips onto a reel,
 10. The method of claim 8, whereinthe female mold is configured to form clips each comprising a topsection having an internal face, an external face, and opposite ends,the clips each further comprising two legs extending from the oppositeends, each leg having an outer edge and an inner edge, and each legfurther comprising a connecting portion projecting outwardly from theouter edge of each leg, at least one connecting portion of each clipbeing joined to a connecting portion of an adjacent clip.
 11. The methodof claim 8, wherein each clip further comprises a shoulder projectingoutwardly from the external face.
 12. The method of claim 11, wherein aspace is defined by the internal face and the inner edges of each leg ofeach clip and each clip further comprises a pin projecting into thespace.
 13. The method of claim 8, wherein a space is defined by theinternal face and the inner edges of each leg of each clip and each clipfurther comprises a pin projecting into the space.
 14. A method ofmanufacturing a plurality of clips, comprising the steps of: extruding amelted thermoplastic resin into thin extrudate; providing a forming toolperpendicular to the extrudate, the extruding tool having a shapecorresponding to the inside of a single clip; forming the single clip bycontacting the extrudate with the forming tool and retracting theforming tool; advancing the extrudate; forming a second single clip bycontacting the extrudate with the forming tool and retracting theforming tool; and cooling the formed clips.
 15. The method of claim 14,further comprising gathering the plurality of clips onto a reel.
 16. Themethod of claim 14, wherein the forming tool is configured to form clipseach comprising a top section having an internal face, an external face,and opposite ends, the clips each further comprising two legs extendingfrom the opposite ends, each leg having an outer edge and an inner edge,and each leg further comprising a connecting portion projectingoutwardly from the outer edge of each leg, at least one connectingportion of each clip being joined to a connecting portion of an adjacentclip.
 17. The method of claim 14, wherein each clip further comprises ashoulder projecting outwardly from the external face.
 18. The method ofclaim 17, wherein a space is defined by the internal face and the inneredges of each leg of each clip and each clip further comprises a pinprojecting into the space.
 19. The method of claim 14, wherein a spaceis defined by the internal face and the inner edges of each leg of eachclip and each clip further comprises a pin projecting into the space.